Session: 03-07 Methanol

Paper Number: 128672

128672 - Methanol-Fired Allam Cycle: Combining Oxy-Fuel Power Cycles With Synthetic E-Fuels 

Direct-fired supercritical CO₂ cycles combine oxy-combustion with supercritical CO₂ to achieve high thermal efficiencies in power plants with carbon capture. The Allam cycle is a transcritical CO₂ oxy-fuel cycle, named after its inventor. It achieves the highest thermal efficiencies compared to other oxy-fuel cycles, with a relatively simple configuration. Currently, most of the research and the commercial development of this cycle focuses on the use of natural gas or coal-derived syngas as a fuel, and oxygen obtained in cryogenic air separation units. Only recently, a few studies have investigated the integration of water electrolysis units that provide the oxygen for combustion. Instead, it appears that currently there are not studies about the use of biofuels or e-fuels in the Allam cycle. However, their use would allow to achieve net negative CO₂ emissions and, possibly, to mitigate the issues of CO₂ storage. This paper proposes and analyzes for the first time a methanol-fired Allam cycle. Methanol is produced from CO₂ hydrogenation using hydrogen from an electrolyzer (e-methanol). Oxygen for methanol combustion is produced in the electrolysis unit. The methanol oxy-combustion generates a stream of flue gases composed uniquely by water vapour and CO₂, being supercritical CO₂ used as a combustion diluent. After turbine expansion and recuperation the water vapour is condensed and used as feed to the electrolyzer. Instead, the CO₂ is partially recycled to the compressor and partially used for methanol production. The aim of the study is to evaluate the performance of the integrated system, and possibly its improvement by identifying any synergy between the Allam cycle and the methanol synthesis. Distinctive features of turbine expansion deriving from the use of methanol as a fuel are highlighted. The results show the optimum operating conditions of the overall system and the energetic and environmental performance, also in comparison with the natural gas fired Allam cycle. 

Presenting Author: Giovanni Manente University of Salento

Presenting Author Biography: Giovanni Manente is Assistant Professor (Ricercatore RTD/B) at the Department of Engineering for Innovation of University of Salento (Italy). He holds a PhD in Energetics, a MS in Mechanical Engineering and a BS in Energy Engineering, from the University of Padova (Italy). In 2017 he received the qualification for Associate Professor positions in Energy Systems and Thermal Machines in Italy. During the PhD his research was focused on power cycles for utilization of low-to-medium temperature heat sources. In this frame, Giovanni spent a one-year internship at the ENEL Thermal Research centre in Pisa (Italy) and seven months at the Massachusetts Institute of Technology in Boston (USA) working on the design and optimization of geothermal organic Rankine cycles (ORCs). In the period June 2019-August 2021 he was Research Fellow (RTD/A equivalent) in the School of Chemical Engineering of University of Birmingham (UK), working on the EU H2020 SO WHAT project about industrial waste heat recovery and valorisation. As a post-doctoral fellow at the University of Padova, Giovanni was Principal Investigator on research projects about low-emission geothermal power plants and integrated solar combined cycles, and worked on the design of axial-flow and radial-inflow turbines for ORCs. He has been lecturer in the course “Power Plant Technology” for the BS in Energy Engineering at the University of Padua for eight consecutive years (2011-2019). He also gave lessons at Graz University of Technology, University of Ljubljana and Lund University within the Erasmus+ Staff Mobility for Teaching program. Since the beginning of 2022 he has been teaching at UniSalento in BS and MS courses. Giovanni is the author or co-author of 51 papers, 27 published on international journals and 24 on international conference proceedings. His publications have received until now over 1850 citations and his H-index is 21 (Scopus).

Authors:

Giovanni Manente University of Salento
Ahtasham Rahim University of Salento
Antonio Ficarella University of Salento